Recently, an electrowetting device using an electrowetting effect has attracted attention. In general, in the electrowetting device, a hydrophilic (high surface-energy) liquid and a hydrophobic (low surface-energy) liquid are filled between a pair of substrates, and at least one of the substrates includes an electrode layer formed on a surface thereof, and a hydrophobic intermediate layer (insulating layer) that is formed on a surface of the electrode layer (for example, refer to Patent Document 1). The electrowetting device has the following characteristic. That is, when a voltage is applied between the hydrophilic liquid and the electrode layer through the hydrophobic intermediate layer, the hydrophilic liquid may be attracted to the hydrophobic intermediate layer, and thus an interface shape between the hydrophilic liquid and the hydrophobic liquid varies. The electrowetting device is used for an optical lens, a display device, and the like by utilizing the characteristic.
However, in an electrowetting display using the electrowetting device for a display device, as a color display method, a method in which a color filter is combined is disclosed.
However, in the display device in which the color filter is combined, when carrying out display with a reflection type, light that has transmitted through the color filter is mixed even when a white color is intended to be displayed. Therefore, light extraction efficiency decreases, and thus the screen becomes dark. In addition, when displaying a single color, a mixed color of the white color and the single color appears, and thus chroma of the single color decreases. As a result, contrast of the display device that is obtained becomes low. As described above, in the electrowetting device using the color filter, there is a problem in that bright and high-contrast color display may not be performed.
In addition, Patent Document 1 discloses a method of forming a hydrophobic liquid layer on a surface of the substrate as a method that is very suitable for manufacturing of the electrowetting display. In the method disclosed in Patent Document 1, the substrate surface is covered with a hydrophilic liquid layer at first. An opening of a dispenser is disposed inside the hydrophilic liquid layer and at an upper side of the substrate surface, the hydrophobic liquid is filled in the dispenser, and thus liquid droplets of the hydrophobic liquid are formed between the opening of the dispenser and the substrate surface. The substrate surface has hydrophobic first regions, and each of the first regions is surrounded by a hydrophilic second region (a pixel wall). When the dispenser is allowed to move along the substrate surface, the liquid droplets of the hydrophobic liquid are attracted to the first region, and the hydrophilic liquid, which comes into contact with the first region, is substituted with the hydrophobic liquid layer, and the hydrophilic liquid, which comes into contact with the second region, is left as is. In the method disclosed in Patent Document 1, a treatment device that is developed for performing filling in the electrowetting device is necessary. In addition, in the method, a relatively long time is taken, and thus there is a problem in that it is difficult to apply the method to a large-sized substrate.
In addition, Patent Document 2 discloses a method of forming an interface shape between a first liquid and a second liquid, one of these being a conductive (hydrophilic) liquid and the other being an insulating (hydrophobic) liquid. In the method, a container having a liquid introduction port and a liquid discharge port is prepared, the first liquid is filled inside the container, and the second liquid is introduced into the container. However, in the method disclosed in Patent Document 2, there is a problem in that the hydrophobic liquid is partially agglomerates and thus unevenness occurs.